1. Field of the Invention
The present invention relates to a fuel saving device and more particularly relates to a system for intermittently interrupting fuel flow to selected cylinders in internal combustion engines having particular applicability to combustion ignition engines.
Various systems can be found in the prior art for blanking or de-activating predetermined cylinders of a combustion engine in order to reduce fuel comsumption. The underlying theory of operation of such systems is simple: reduce or shut-off fuel to selected cylinders under low load conditions to achieve better fuel economy. Various patents can be found showing systems which operate on this principle.
2. Description of Related Art
U.S. Pat. No. 4,080,947 discloses a system of controlling ignition in multi-cylinder engines in which the air-fuel mixture in one or more of the cylinders is cut-off depending upon load conditions. The system uses signals detected by the vehicle speed sensor, engine RPM sensor, and intake pressure senser.
U.S. Pat. No. 4,434,767 discloses a control system which controls the number of working cylinders so that actual torque requirements are maintained. Engine speed is detected and the system operates to maintain constant intake pressure.
U.S. Pat. No. 4,509,488 shows an apparatus in which working strokes of a multi-cylinder engine are skipped in approximate uniform distribution dependent on the load.
U.S. Pat. No. 4,541,387 shows a system for controlling fuel injection having fuel injection control circuit responsive to the load on the engine to selectively cut-off fuel to a corresponding cylinder.
U.S. Pat. No. 4,552,114 shows an apparatus for controlling the number of operative cylinders in a diesel engine having a fuel injector pump which is controlled by an electromagnetic valve. A control circuit detects the operating condition of the engine to determine the number of cylinders to be operated. The system includes a register for storing the cylinder control data from the control circuit, a pulse generating circuit responsive to the cylinder pulse and synchronized with shaft rotation and the stored value of the register to control the application of the valve opening pulses to the electromagnetic valve.
U.S. Pat. No. 4,640,241 shows a skip-cylinder system having a decision circuit which selects the cylinder or cylinders which are to be operative.
U.S. Pat. No. 4,909,223 discloses an air-fuel ratio control apparatus which senses the number of parameters including the air-fuel ratio, crank angle for detecting engine speed and the position of the piston in each cylinder as well as intake air flow.
U.S. Pat. No. 4,204,512 discloses a cylinder deactivator system for an internal combustion engine. Each valve train has a rocker lever assembly and a rocker lever shaft The rocker lever assembly has a first member and a second member that are joined at the mid-section of the rocker lever assembly and are commonly mounted on a shaft. A fluid pressure cylinder assembly has a piston rod and a pawl mounted on the end of the piston rod. Two of the opposite surfaces of the pawl mate with shoulder surfaces of the first and second members in the manner of a keystone when the particular cylinder is operational. In the configuration applicable to diesel engines, a fluid pressure assembly also controls the operation of the fuel injector.
In addition to the foregoing, other systems can be found which de-activate or blank-out cylinders of internal combustion engines in order to conserve fuel. However, most of these systems have not achieved any substantial degree of success or acceptance due either to their complexity, their lack of reliability or failure to quickly re-activate blanked cylinders when additional power is needed.
Accordingly, it is an object of the present invention to provide a cylinder blanking system for internal combustion engines.
It is another object of the present invention to provide a cylinder de-activation system that monitors turbo pressure and may also monitor engine RPM and is responsive to these engine operating characteristics.
It is an object of the invention to provide a cylinder blanking system which senses selected engine parameters and initiates blanking only after certain conditions exist for a predetermined period of time.
It is another object of the present invention to provide a cylinder de-activation system for internal combustion engines which may be manually overriden by the operator.
It is another object of the present invention to provide a novel cylinder blanking system which may be retrofit to most conventional combustion ignition engines.
It is a specific object of the present invention to provide a cylinder blanking system which blanks selected cylinders by interrupting fuel flow by holding a fuel system component such as a fuel injector in a non-actuated position during cylinder blanking.